As textile substrates age, their color tends to fade or yellow due to exposure to light, air, soil, and natural degradation of the fibers that comprise the substrates. To counteract this unwanted effect, laundry detergent manufacturers incorporate hueing agents into their products. Thus, the purpose of hueing agents is typically to visually brighten these textile substrates and counteract the fading and yellowing of the textile substrates.
Detergent manufacturers continue to seek to incorporate hueing dyes into their laundry detergent products, especially their laundry detergent powders. Detergent manufacturers prefer to incorporate detergent ingredients into a spray-dried laundry detergent base powder, by crutching and spray-drying the detergent ingredients: as this is an easy and cost effective means for their incorporation. However, when hueing dyes are incorporated into the crutcher, their colour determines the colour of the spray-dried laundry detergent base powder, which may not be preferred by the consumer. This has led detergent manufacturers to design separate particles for their hueing dyes.
These particles need to exhibit good storage stability, especially in conditions of high humidity, the dye must not bleed out of the particle and affect the colour of the base laundry powder, this is especially important in the presence of non-ionic detersive surfactant that may be present in the detergent formulation, and especially when sprayed onto the bulk of the powder.
These hueing dye particles must still rapidly dissolve in water, even cold water, during the laundering process, and the particles must rapidly deposit dye onto the fabric without causing dye damage such as spot staining.
The inventors have found that a unique combination of a specific type of hueing dye, when incorporated into a particle that additionally comprises clay, the resultant particle exhibits both good storage stability profile, good fabric deposition and does not impact the visual appearance of the base detergent powder when admixed thereto.
The particle exhibits an excellent storage stability profile with very little bleeding of the hueing dye from the particle, exhibits excellent fabric deposition of the hueing dye during a laundering process without causing any spot staining of the fabric, and does not impact the visual appearance of a laundry detergent powder when incorporated therein.